Comparative studies on calpain activity of different muscles of cattle, camel, sheep and goat

Tenderness is the single most important factor influencing consumer acceptance of meat. The calpain proteolytic system is known to be responsible for the post-mortem tenderization of meat. The purpose of this study was to determine and compare the tensile strength and total calpain activities in different muscles of camel, cattle, sheep and goat. In camels, the effect of age and sex of animal was also studied. Twenty-four animals (camel, cattle, sheep and goat) were sampled randomly after slaughtering. Samples from biceps femoris, longissimus dorsi and triceps brachii and heart were obtained from each animal. The tensile strength was calculated using an Instron Universal testing machine. After homogenization of samples in 0.1 M NaCl and centrifugation, total calpain activity was determined by fluorometric method. Despite significant differences in tensile strength, no significant difference (P>0.05) was observed among calpain activities of different muscles in each species. Inter-species differences however, were significant (P<0.05). In all muscles, the highest calpain activity was found in camel (3.08–5.36 RFU/mg protein) followed by cattle (3.65–4.43 RFU/mg protein), sheep (1.17–2.82 RFU/mg protein) and goat (1.24–2.23 RFU/mg protein). No significant differences were observed between camel and cattle and also between sheep and goat in tensile strength (P>0.05). In camel, adult animals had higher calpain activity and tensile strength than youngs; sex had no significant effects. Correlation coefficients of calpain activity and tensile strength were negative and not significant in all species. In conclusion, meats from different species might show different degrees of tenderness, partly due to the difference in their calpain activity.